Alternatives to Chlorpyriphos for Tobacco Growers
Chlorpyriphos is an organophosphate insecticide that has been the topic of recent regulatory review. The federal Environmental Protection Agency decided not to revoke chlorpyriphos tolerances in 2019 which would have effectively banned its use. Despite this, some tobacco purchasers have indicated that they will not buy crop treated with chlorpyriphos.
Because of this, growers have contacted us asking for guidance on alternatives to chlorpyriphos. Fortunately this is a fairly easy question to answer, because in almost all NC tobacco fields, chlorpyriphos use is not necessary.
Chlorpyriphos (labeled as Lorsban Advanced, Warhawk and others) can only be applied pre transplant in tobacco, and these applications have typically been targeted at soil pests such as wireworm and white fringed beetle or cutworms.
For soil pests, greenhouse applications of imidacloprid (Admire Pro and others) can be made at the maximum labeled rate, which will provide similar suppression of wireworms as chlorpyriphos.
Cutworms rarely reach damaging numbers in NC tobacco fields, so a preventative treatment of chlorpyriphos targeting them is almost never warranted. Instead, growers with a history of cutworm damage should scout those fields weekly the first four weeks after transplant and take management action if clipped plants approach 10% loss. Foliar applications of lambda-cyhalothrin, bifenthrin, or other caterpillar materials are all good options during this period but should only be used if insects are directly observed.